Automatic flatiron



Sept. l, 1936 E. A. Rol-:HL ET Al.

AUTOMATIC FLATIRON y 2 Sheets-Sheet l Filed Oct. 15, 1932 Il Il I @a mj 2 Sheets-Sheet 2 E. A. ROEHL ET AL AUTOMATIC FLATIRON Filed' Oct. l5, 1932 Sept. 1, 1936.

444i/ if .enfrenta-'ric meinen Edward il. loehl, Frank W., Carpenter, and

Maurice EL. "Warner, Minneapolis, Minn., assigncrs to Bcrninion Electrical Mfg. Co., Minneapsiis, Minn., a corporation of Minnesota Application @nicher l5, 31.932, Seriali No. 637,936

ll @laila @ur invention relates to electrical heating appiiances and particularly to automatic electric idatirons.

l't is an object of our invention to provide, `in an electrically heated ilatiron, a novel, very sensitive, and inexpensive means for automatically maintaining the sole plate of the fiatiron at a substantially constant predetermined temperature.

.another object is to provide temperature regulating means of the class described which may be easily and rapidly adjusted to maintain various temperatures and wherein the temperature of the sole plate is the index by which the action of the regulating means is governed.

Still another object is to provide an electrically heated flat iron wherein the sole plate'is constructed of material having a relatively high thermal coeilicient of expansion, and wherein the relative movement aiorded by unequal expansion and contraction of said sole plate and a member constructed of material having a relatively low thermal coeiicient of expansion is utilized for actuating electrical contacts connected in the circuit of the heating element of the iiat iron.

These and other objects and advantages of the invention will be more fully set forth in the following description made in connection with the accompanying drawings, in which like reference characters refer to similar parts throughout the several views, and in which:-

Fig. 1 is a side view of our flat iron;

Fig. 2 is a top view with the handle, casing, and pressure plate removed;

Fig. 3 is a vertical cross sectional view taken along the line 3 3 of Fig. 2 as indicated by the arrows;

Fig. 4 is a longitudinal vertical sectional view taken along the line 4--4 of Fig. 2 as indicated by the arrows;

Fig. 5 is a top view of another form of our invention with the handle, casing, and pressure plate removed;

Fig. 6 is a longitudinal vertical sectional view taken along the line 6 6 of Fig. 5 as indicated by the arrows, and

Fig. 7 is an enlarged, vertical sectional detailed view of the insulated connecting element between the lower contact arm and the actuating lever therebelow.

Referring to the drawings, and particularly to Figs. 1, 2, 3 and 4, a sole plate III is of conventional shape, but is constructed of aluminum or other metal having a relatively high thermal coeiiicient of expansion. Above the sole plate I0 is an electrical heating element iI of conventional `form enclosed by an insulating and heat conducting casing i2, formed of mica or other heat resistant electrical insulating material. From slightly forward of the middle thereof to the rear end thereof the mica casing i2 has a portion cut away along and adjacent its longitudinal center line to leave a V-shaped opening i2b as shown in Fig. 2. Above the mica casing i 2 is a pressure plate I3, the lower side of which is recessed above the cut away portion of the mica casing I2 as best shown in Figs. 3 and 4. Screws i4, passing through apertures in the pressure plate I3,

through apertures I2a in the mica casing I2, and 15 into internally screw threaded apertures in the sole plate I0, pull the pressure plate I3 toward the sole plate I0 to rmly clamp the heating element II and its mica casing I2 between the pressure plate I2 and the sole plate I0.

Each of two fiat resilient metal arms I5 and I6, disposed one above the other, parallel to each other, and'in general parallel to the sole plate I0, carries at its outer end, one of a pair of coacting electrical contacts I5a and I5a. 'I'he contact carrying arms I5 and I6 are disposed above and are longitudinally aligned with the V-shaped opening I2b in the mica casing I2 with their inner ends toward the rear. The inner or rear ends of the arms I5 and I6 are secured to the sole plate Ill by means of screws I1, insulating spacers I8 being interposed between, above, and below the arms I5 and I6, and the screws I1 being provided with insulating sleeves (not shown) and extending through aligned apertures in the arms I5 and I5 and the spacers I8 in a well known manner. The rearm'ost portion of each of the arms I5 and I 6 extends a short distance beyond the rear edges of the spacers I8 to form terminals I5b,a.nd IIb.

A strip I9, formed of invar steel or other suitable metal either having a relatively low thermal coefficient of expansion or a zero thermal coeillcient of expansion, is clamped at its rearward end between the lowermost one of the spacers I8 and the sole vplate ill and extends forwardly to a point near the forward end of the sole plate I0 whereat it is secured to the sole plate I0 by means of a screw engaged in a suitable screw threaded aperture in the sole plate. The portion of the strip I9 lying beneath the medial and outer portions `if the contact carrying arms I5 and I6 is arched upwardly and carries on its uppermost portion an upwardly projecting insulating button 2 I, the upper side of which is in contact with the lowern'rost contact carrying arm I. 'I'he arm I6 is so bent that it-continually urges itself toward the button 2l so as to maintain contact therewith.

The contact carrying arms I5 and i6 are housed in the recessed lower side of the pressure plate I3 and a portion of the pressure plate I3 extends horizontally thereabove. Above and aligned with the outer portion of the 'uppermost contact carrying arm I5, a vertically disposed screw threaded adjustment member 22 is engaged in a screw threaded aperture in the pressure plate I3 above which it extends a short distance. An insulating pin 23 is retained at its upper end in a recess in the lower end of the adjustment member 22 and at its lower end bears upon the contact carrying arm I5. "I'he contact arm l5 is so bent that it urges itself upwardly to maintain contact with the pin 23. The upper end of the adjustment is of a square or other suitable shape. An adjustment lever 24 has a downwardly extending hub 24a. in the lowerend of which is a recess shaped to fit and engage with the upper end of the adjustment member 22.

A casing or shell 25 and handle supports 26, all of conventional form, are secured to the previously described structure in a well known manner by means of`screws 21 passing through apertures therein and engaged with' screw threaded apertures in the upper side of the pressure plate I3,

-as shown in Fig. 4. A handle 28, of a conventional type, is secured at its respective ends to the upper portions of the handle supports 25. A pin 32 projecting radially outwardly from the hub 24a is situated to strike the casing 25 to prevent vertical displacement of the hub and lever.

Connection prongs 29 of conventional form are .insulatedly mounted in the upper rear portion of the casing 25, as shown inl Fig. 4. O ne of the prongs 29 is electrically connected to one terminal of the heating element II, the remaining terminal of the heating element II is connected to the terminal I6b associated with the contact carrying arm I6, and the terminal I5b associated -with the remaining one of the prongs 29. From the above it is obvious that the heating element is connected to the prongs 29 .with the contacts I5a and laconnected in series therewith.

A guide 30, for an electrical connection plug, and a stand 3|, both of conventional form, are secured to the rear'portion of the casing 2.5, as shown in Fig.' 1.

Preferably, a dial 32 and a pointer 24a are associated with the adjustment lever 24 to assist in positioning the lever to obtain various desired temperatures.

Operation When our flatiron is placed in operation, the prongs 29 are connected to a source of electrical energy by means of a plug equipped electrical cord of conventional form. When the iron is rst connected and is cold, the 'pair of contacts I5al and Ilia are closed, and, hence electrical current will flow from one of the prongs 29, through the heating element II, through the closed pair of contacts I5a and I-Ga to the remaining one of the prongs 29,. and heat produced in the heating element I I by means of the electrical current will ilow into thev sole plate I 0 and incidentally into other parts of the flatiron structure.

As the various parts become heated they will expand and the sole plate I0, since it has a relatively high thermal co-eiicient of expansion, will increase in length to a relatively great extent.

The flat strip I9, since it has a relatively low thermal-co-efilcient of expansion, will increase in length only very slightly'and hence will be tensioned longitudinally by the relatively great expansion of the sole plate. 'I'he said tensioning of longitudinal pulling of strip I 9 attens the.arched portion thereof.v Flattening of the arched portion of the strip I9 draws the insulating button 2| downwardly to permit the contact Ia to move downwardly away from the contact i5a to open the electrical circuit to the heating element II and hence prevent further increase in the ternperature of the sole plate. As the temperature of the sole plate I0 decreases the sole plate will contract at a greater rate than the strip i9 and hence will cause the strip to arch upwardly to again close the contacts I5a and |512 to again' close the circuit to the heating element with the result that heat will again be delivered to the sole plate. The above cycle will be repeated as long as the iron is connected to a source of electrical energy and the ratio between the lengths of time during which the circuit is closed and the lengths of time during which the circuit is open will vary in accordance with the rate of delivery of heat to the material being ironed and the air surround- Y ing the iron.` It is obvious that the operation of the contacts is governed directly by the temperature of the sole plate and that the soleplate will be maintained at a substantially constant temperature, the variation in temperature being between verynarrow limits.

Swinging of the lever ,24 to one side or the other will rotate the screw threaded adjustment member I22 and obviously cause the member 22, the insulating pin 23 and the upper contact arm I5 to move upwardly or downwardly according to the direction of movement of the lever 24. If the upper contact arm I5 is lowered, the Hattening of the arched strip I9 and hence the expansion of the sole plate I0 causing the flattening will proceed to an increased extent .before the contacts will open and hence the temperature at which the sole plate I0 will be maintained will be increased. Conversely, raising the upper contact will lower the temperature. It obviously follows'that the temperature to be maintained may be adjusted as desired by properly positioning the adjustment lever 24.

-Anotherform of our invention, shown in Figs. 5, 6 and 7, includes a sole plate 40, a pressure plate 4I, a casing 42, a heating element 43, and a mica. casing 44 forA the heating element,all connected together in the same mannerl as the corresponding parts of therst described form. The sole plate 40 is formed of material having a relatively high thermal coeiiicient of expansion.

The mica casing 44 is similar to the micacasing I2 of the rst described form and isvprovided with a U-shaped opening 44a similar to the opening I2a of the mica 4casing I 2.

The sole plate 40 has a recess 45 in the upper side thereof disposed below the U-shaped opening 44a and a groove 46 extending some distance forwardly therefrom. In the bottom of the outer end of the groove 46 there is an aperture 41 extending downwardly into the sole plate 40.

A substantially horizontal lever 48 has at its inner end portion an apertured ear 48a depending from each side thereof. A pin 49 extends through the apertured poriilon's of the earsv 48a and through an apertured lug portion 50a of a member 50, the lug portion 50a being disposed between the ears 48a and the member 5U being secured to the bottom of the rear portion of the recess 45in, 75

medial portion thereof is supported at its respecl tive ends in aligned apertures in the upper por-A tions of the ears 48a.

A relatively long thin rod 53 formed of material having a relatively low thermal coeilicient of expansion has an angularly bent forward end portion disposed in the aperture 41 from which the rod extends rearwardly in the groove 46 with its rearward end extending through the diametrical aperture in the shortl rod 52. The rear portion of the rod 53 is externally screw threaded and carries an internally screw threaded sleeve 54 the forward end of which is in contact with the rearward side of the rod 52. i

Above the lever 48 is a pair of thin fiat forwardly extending arms 55 and 56 disposed one above the other and parallel to each other. The arms 55 and 56 each carries one of a pair of coacting electrical contacts 55a and 56a. The rearward portions of the arms 55 and 56 have insulating spacers 51 above, below, and between them. Screws 58, provided with insulating sleeves, pass downwardly through aligned' apertures in a horizontally disposed web portion o f a channel shaped supporting bracket 59, the spacers 51, and the arms 55 and 56, and are threadedly engaged in internally screw threaded apertures in a plate 6D located immediately below the lowermost one of the spaces 51. The screws 58 are drawn up snugly to clamp together the elements through which they extend. The depending flange portions of the channel shaped supporting bracket rest upon the upper surface ofthe soleplate 40.

A hanged plug 6I, formed of insulating material and having a metal loop 62 depending therefrom is carried in an aperture in the outer end portion -of the lower contact carrying arm 56 as shown in Figs. 6 and 7. The outer end of the lever 4B is of reduced width and extends through the loop 62. l

An internally screw threaded bushing, disposed in an aperture in the pressure plate 4I, is spot welded or otherwise secured to the upper side of the web of the channel shaped supporting bracket 59 in alignment with an aperture therethrough located above the contact ca'rrying arm 55. An externally screw threaded adjustment element 64, having a pin 65 formed of insulating material projecting from the lower end thereof, is threadedly engaged at its lower end in the bushing 63. The lewenencl of the insulating pin 65 bears upon the upper side of the upper contact carrying arm 55. The arm 55 is so bent that it urges itself upwardly against the insulating pin 65 to maintain abutment therewith. Anv adjustment lever 66 has a depending hub portion 66a extending downwardly through an aperture in the casing. The lower end of the hub 66a carries a member nonrotatively engaged in a non-circular recess in the upper end of the adjustment member 64. A pin 61, extending radially outwardly from the hub 66a prevents upward displacement of the lever 66 and the hub 66a.

Terminal prongs 68 similar to the prongs 29 of the nrst described form and similarly mounted are connected with the heating element -43 and the contact carrying arms 55 and 56 in the manner described in connection with the corresponding parts of the rst described form.

In operation, as the temperature of the iron rises/and the sole plate, since it is formed of metal having a relatively high thermal coeillcient of expansion, increases its length to a relatively great extent and the rod 53, since it is formed of metal having a relatively low thermal coeiiicient of expansion, increases its length only very slightly. The result is that the rod 53 is pulled forwardly to deflect the lever 48 downwardly and the lever 48 pulls the lower contact arm 56 away from the upper contact arm 55 to break the electrical circuit to the heating element and hence prevent further production of heat and increase in temperature. With the exception of the above, the operation of this form of our invention is identical with the operation of the first described form.

It is apparent that we have invented a novel, simple, rugged, inexpensive, and sensitive form of electrically heated hat iron wherein means is provided for automatically maintaining the temperature oi the sole plate within close limits, and wherein adjustment means is provided for adjusting the temperature at which the sole plate will be maintained.

It will, of course, be understood that various changes may be made in the form', details, proportions and arrangement of the parts, without departing from the scope of my invention, which, generally stated, consists in a device capable of carrying out the objects above set forth and in the novel parts and combinations of parts disclosed and defined in the appended claims.

Attention is called to the Aunusual sensitivity of our heat controlling mechanism. Formerly, automatic fiatirons and the like have had the thermostatic orsensitive element disposed deep in the interior of the device and usually surrounded by air. With the sole plate itself constituting the sensitive element, small changes of temperature in the sole plate due to rapid transfer of heat cause the circuit through the heating element to be quickly closed. The actual part of the device which is impressed against the clothes or articles heated is therefore the index of the temperature at which it is maintained. In actual tests with the iron up to temperature and the circuit through the heating element open, when the sole plate of the iron or even a small portion, such as the tip thereof, is placed against a damp article of clothing, the circuit will be re-close'd in less than 20 seconds.

What is claimed isz- In a heating device, a heat transmissive plate for applying heat to material to be treated, an electrical heating element associated with said plate for heating the same, said plate being constructed of material having a relatively high thermal co-efiicient of expansion, an elongated member of material having a relatively low thermal co-eflicient of expansion, said member being secured at one of its ends to a point on said plate, a bell-crank having one relatively long arm disposed substantially parallel to said plate and a depending shorter arm swingably connected at its free end to a point on said plate widely spaced from said first point, the remaining end of said elongated member being connected to said bell-crank at the junction of said arms, and an electric contact means electrically connected in the circuit of said heating element and having mechanical actuating connections with the free end of the longer arm of said bell-crank whereby heating and cooling of .said plate vwill respectively cause opening and closing of `said contact means.

EDWARD A. ROEHL. FRANK W. CARPENTER. MAURICE L. WARNER. 

